Control valves are commonly used in process control systems to control the flow of process fluids (e.g., liquids or gases). A control valve typically includes an actuator apparatus (e.g., a pneumatic actuator, a hydraulic actuator, etc.) operatively coupled to the flow control member of a fluid valve to automate the control valve. In operation, a controller is often employed to supply a control fluid (e.g., air) to the actuator, which, in turn, positions the flow control member (e.g., a valve gate, a plug, a closure member, etc.) to a desired position relative to a valve seat to control or regulate the fluid flow through the valve.
Angle valves are typically used in the chemical and hydrocarbon industries where control of residual oils or other liquids with coking properties is necessary. These valves use a swept flow passage and nozzle configuration in the throat region where the throat is below the 90° turn to normalize fluid flow and equally distribute fluid across the choking area of the valve plug, thereby improving valve performance.
Balanced plug and valve designs are frequently used to reduce forces required for the actuator to open and close the valve. Static pressure imbalances are canceled by equalizing pressure on the bottom and the top of the plug, thereby allowing the actuator to open and close the valve plug more easily and require less energy and force to do so. Accordingly, smaller, less expensive actuators can be used with these control valves.
Typically, valve plugs are balanced via ports or longitudinal internal passageways formed through the plug. Because balanced valve plugs are used in conjunction with globe valve designs, the plugs are generally short in length and can easily be drilled using a standard drilling or machining process.
As shown in FIG. 1, some known angle valves 100 include a valve body 102 forming a channel 104 defining a fluid flow path that extends from an inlet 106 of the valve body 102 to an outlet 108 of the valve body via a gallery 110 disposed between the inlet 106 and the outlet 108. The valve body 102 further defines an opening 112 disposed in communication with the gallery 110. A valve seat 111 is at least partially formed by the valve body 102 and is disposed in the gallery 110.
A valve bonnet 114 at least partially covers the opening 112 of the valve body 102. A valve stem 116 has a first portion 116a and a second portion 116b, and is at least partially disposed within the opening 112. A flow control member 120 in the form of a plug is coupled to the valve stem 116. The plug 120 is adapted to be moved into and out of sealing contact with the valve seat 111. A liner guide 118 surrounds the plug 120 and assists in guiding movement of the plug 120. It is understood that the valve 100 includes any number of additional components to assist in operation such as, for example, a retainer, a flange, a valve stem spring, any number of gaskets, seat rings, washers, and/or packing rings.
In operation, a controller (not shown) may provide a control signal to an actuator (not shown) operably coupled to the valve stem 116. This control signal causes the actuator to move the valve stem 116 such that the plug 120 moves in a rectilinear path relative to the valve seat 111 to control fluid flow through the valve body 102.
As illustrated in FIG. 1, the liner guide 118 extends from the bonnet 114 into the gallery 110. This protrusion, combined with the elongated configuration of the plug 120, create a flow obstruction that reduces the flow efficiency of the valve. Further, angle valves use plugs 120 that are unbalanced because choking gas valves, such as the angle valve 100, have an elongated shape, and thus an elongated plug 120, and the extended length and small diameter that would be required of a longitudinal internal passageway in the plug 120 cannot be reliably formed. Any insert used to form such an opening would likely break or become damaged during the manufacturing process and additionally may not be able to be removed from the valve plug 120.